In a conference call with reporters on Thursday, Penn asserted that Obama can’t win because he has been unable to beat Hillary in several big states that are key to success for Democrats in the November.

Clinton won in Ohio and Florida, two important swing states, and also won in the three largest states, California, New York and Texas.

The Clinton campaign is now stressing the importance of the April 22 primary in Pennsylvania, where most polls show Hillary with a double-digit lead over Obama.

“We believe fundamentally that [Pennsylvania] provides a very significant test of who can really win the general election,” Penn said.

“We believe this will again show that Hillary is ready to win and that Senator Obama really can’t win the general election.”

Penn’s comments were “surprising because it’s generally considered off limits for candidates from the same party to denounce another as unelectable,” noted Canada.com, which reported the remarks.

“It was particularly striking since Clinton, only last week, suggested the possibility she and Obama could share the Democratic ticket in the fall.”